Governor

Governors were used on early 100 through 300 series trucks with 6-225, 6-251, 8-318, 8-361 and 8-413 engines to limit maximum engine speeds.

Three different governors were used: The King-Seeley governor, the Hoof Velocity governor and the Pierce governor. Each governor is clearly marked as to its identity.

The King-Seeley and the Hoof are velocity types and are mounted under the carburetor.

The Pierce is a mechanical type and is gear driven from the distributor shaft.

REMOVAL & INSTALLATION

King-Seeley and Hoof Velocity Types

To remove the governor, first remove the carburetor, then lift the governor off the studs and discard the gasket.

On 6-225 models with a closed crankcase ventilation system, spacer #2205857 is required between the carburetor and governor.

Installation is the reverse of removal. The Hoof governor must be installed with the vacuum unit facing away from the engine.

Pierce Mechanical Type Governor

Remove the distributor.

Disconnect the oil line.

Disconnect the governor-to-carburetor linkage.

Disconnect the tachometer cable.

Remove the hold-down bolt from the lower end of the housing, that also holds down the distributor.

Remove the distributor adaptor and governor from the engine as an assembly.

When installing the unit, the distributor intermediate driveshaft must be in proper mesh with the camshaft gear before installing the adaptor. Connect all cables and lines, then install the distributor. Adjust the governor.

ADJUSTMENTS FOR KING-SEELEY GOVERNOR

Speed

Check the governor cover plate for the proper identification and determine the speed range:

Hold the speed screw from turning with the hex wrench, while turning the calibrating nut counterclockwise
1
/
4
turn at a time, until the governor response is satisfactory.

Reset the governor speed setting.

ADJUSTMENTS FOR HOOF VELOCITY GOVERNOR

Speed

See Figure 1

Check the governor body for proper identification, then determine the maximum speed range:

Fig. Fig. 1: Hoof governor adjustment

S-30M-142 6-cyl.- 2,600-3,200

S-30M-142 8-cyl.-2,700-4,000

S20DM-68-3,600-4,000

Turn the adjusting screw clockwise for higher speed; counterclockwise for lower speed. Final adjustment must always be made in a clockwise direction. In other words, if the setting is too high, turn the screw counterclockwise back past the desired setting, then clockwise to the correct speed.

Turn the screw counterclockwise
1
/
4
turn at a time until the response is satisfactory.

When the adjustment is made, turn the speed screw clockwise, 1 turn for each
1
/
4
turn made to the secondary screw.

ADJUSTMENTS FOR PIERCE GOVERNOR

Before making any adjustments, make sure that the carburetor linkage is adjusted to permit wide-open throttle when the governor lever is fully forward.

Governor-to-Carburetor Rod

See Figure 2

Hold the rod so that the throttle is wide-open. Adjust the rod length at the ball end so that 0.02 in. (0.5mm) clearance exists between the stops on the governor lever.

On the 4-bbl carburetor, binding may exist. If it does, check the carburetor mounting gasket. It may be reversed. The large holes go to the rear.

Attach the rod to the governor, making sure that the ball joints at each end of the rod are in line to prevent binding. Tighten the locknuts.

Move the entire governor arm assembly to the closed position and check for interference with any other components. There should be a minimum of
1
/
8
in. (3mm) clearance between the governor arm and any other component.

Fig. Fig. 2: Pierce governor linkage adjustment

Allow the governor arm to return to the wide-open throttle position and make sure that there is
1
/
4
in. (6mm) minimum clearance between the arm and the air cleaner.

Recheck the stop clearance.

If the throttle plates do not stay open, check the governor upper arm lever spring for distortion. In the relaxed position, the spring should be completely solid and require a 9 (kg) effort to pull it
1
/
4
in. (6mm).

Carburetor-to-Bell Crank Rod

Remove the return spring. Make sure that the accelerator pedal is bottoming on the floor, and is not being held up by the rubber grommet or floor mat.

With the governor holding the throttle wide-open, adjust the carburetor-to-bell crank rod by turning the ball end so that the carburetor floating lever just allows the throttle to go wide-open.

Increase the rod length by 2 turns of the ball end to provide about
1
/
16
in. (1mm) overtravel of the floating lever beyond the wide-open throttle position.

Make sure that both ball ends are at least 4 full turns onto the rod.

Attach the ball stud to the bell crank.

Tighten the stop nuts at the ball ends. Make sure that both ball ends are indexed so that there is no binding.

Make sure that the throttle overcenter stop is bolted to the carburetor. It should be lined up so that the throttle rod ball joint end will contact the stop if there is excessive lever travel beyond the wide-open throttle position. When properly installed, there should be
1
/
8
-
1
/
4
in. (3-6mm) clearance between the stop and the end of the throttle rod ball joint when the pedal is on the floor.

Governor No-load Speed Setting

Run the engine to normal operating temperature.

Increase the engine speed until the governor begins control. This should occur at 3,600-3,700 rpm.

If necessary, break the seal and adjust the speed by changing tension on the governor spring. One turn of the nut changes the speed by 50 rpm.